After our equipment passes all the necessary tests, the next step in our production line is the surface finish. This phase consists of three parts: surface preparation, application of the paint or desired finish, and quality control.
Surface preparation
In order to paint carbon steel equipment, it is necessary to prepare its surface to ensure proper paint adhesion. This is achieved by surface sand blasting. This treatment is applied to all surfaces of the piece, both inside and outside, and allows us to leave a clean surface with a suitable roughness for the application of paint. In this process, it is important to protect the parts that we do not want to be sand blasted, such as machined raised faces.
Once the piece has been sandblasted, it is cleaned and prepared for the painting phase.
In the case of stainless steel, a surface finish is also applied, such as shot blasting with a stainless steel ball. This is not as abrasive as sandblasting, since we do not have to apply a coat of paint afterwards, so the surface finish does not need to be as rough.
The two processes, sand blasting and shot blasting, are done independently to avoid any type of contamination.
Painting
The paint application can be inside or outside of the piece, depending on the needs and manufacturing specifications, although it is most common for it to be only outside.
Before painting any equipment, we check the following points:
1. The conditions of the process where the equipment is going to work to select the appropriate type of paint by temperature, compatibility, finish, etc.
2. The degree of surface protection that we want to give to the piece.
Finishing paints are usually polyurethanes, which can withstand temperatures of up to approximately 120ºC. If the equipment works at a higher temperature, then it is necessary to apply an anti-heat paint, with which we can protect the surface of the equipment from temperatures of up to 400ºC. When we talk about the degree of protection, we apply a standard C3 degree of protection to all our products, although we can reach C4 and C5H protections according to the client’s requirements. These degrees of protection are achieved by combining suitable primers and finishes, as well as applying different thicknesses in each layer.
For the application of an interior paint, it is also important to know the fluid that will circulate inside the equipment since, if it is water or fuel, we must select the appropriate paint for each case.
Also in this phase we can apply internal coatings, such as teflon or ebonite for high demanding applications, following customer requirements if needed.
Quality control
Once the paint has been applied, we carry out several tests on the equipment to verify its correct application, such as thickness measurements at different points of the piece and surface adhesion tests.
If the controls have been satisfactory, our equipment is ready to move on to the next phase: final assembly.